By now you have probably seen the footage of long-deceased rapper Tupac Shakur performing at Coachella (above: NSFW, language). Whether or not you thought you thought it was creepy, the technology behind the holographic resurrection is actually pretty cool.
The blend of previously recorded live footage and CGI was created by Digital Domain — James Cameron’s visual effects company that was also responsible for the ersatz Brad Pitt in The Curious Case of Benjamin Button — under the supervision of Dr. Dre.
AV Concepts, the company that handled the projection, has done similar things in the past, most notably Madonna’s performance with Gorillaz at the 2005 Grammy Awards. As New Scientist points out, the technology is based on a concept that’s been around since the 1800s. It’s called Pepper’s Ghost and it works by partially reflecting light off a piece of glass from a hidden room.
You might have recognized it from the Haunted Mansion ride at Disneyland; at Coachella, they achieved the effect by rigging up a custom, 30-foot by 13-foot screen that could be lowered in seconds for a hologram that’s slightly more advanced than Disney’s dancing ghosts.
While AV Concepts declined to speak to TIME.com because they didn’t want to reveal their secrets before the second weekend of the music festival, according to MTV the hologram took around four months to create and similar holograms in the past have cost between $100,000 to $400,000 to put on.
So, just how real is the holographic Tupac? It already has its own Twitter account.